The invention is based on a method for preventing excessive currents in a welding converter that generates a two-phase, pulse-width-modulated a.c. current from a rectified mains a.c. current using power semiconductors, which generated current is supplied to the primary side of a welding transformer, as is known in a commercially-available welding machine in which monitoring is provided to prevent excessive current. Also, in this arrangement the magnetization of the welding transformer is adjusted by the control system. Current monitoring is effected from the secondary side of the welding transformer. Because of this, errors in the primary circuit may possibly be falsified or identified too late, which can result in damage to the power semiconductors.
It is an object of the invention to disclose a method and an associated arrangement that permits better protection of the power semiconductor against excessive currents. It is further an object of the invention to disclose an arrangement that permits simplification of the location of the cause of the error when overcurrent occurs in the primary circuit.